Program Structure Advise

[dcaragher]

I need to write a LabView program for somewhat of a basic test stand, but what like to get some ideas on how to impliment it . Here is an description / outline of the program reqiurements.

The purpose of the test stand is to test filtration media samples. There will be up to 5 samples tested at a time. There will be 2 modes of testing.

One will be a constant flow test and the other will be a constant pressure test. In the constant flow test, a parastaltic pump will be set at a constant flow rate with a seperate feed through each sample. The fluid will then be collected downstream of the filter in beakers. The fluid will very, but will contain some particulate that will load up the filter media samples at different rates depending on the filter media type. This will create different pressure drops across each filter. 5 pressure transducers will be used to measure the increasing pressure drops as each of the filter samples load. After X time the pump will be manually stopped. As the test runs, elapsed time and pressure drop data will be logged to a file.

The second mode will be a Constant Pressure test. In this case, a reservoir will be filled with the test fluid and a constant pressure will be applied via pressure regulator. The fluid will be forced through each filter sample at a constant pressure (therefore constant pressure drop across each filter). 5 small scales ( 0-6000g, 0-5 vdc output) will be used to calculate decreasing flow rate as the filters load up. To calculate flow, weight measurements will be taken at x second intervals. Therefore, an average mass / sec flow rate can be calculated. The constant applied pressure and calculated flow rate will be logged to a file with a time stamp. As in the Constant pressure test, the test will be stopped manually.

The program will need to prompt the user for a test data filename.

Then prompt user for test info.

Test Date : ( from clock )

Test Time : ( from clock )

User: (string control)

Customer: (string control)

Test Fluid: (string control)

Test Type ( This will be a selection of either Constant Flow or Constant Pressure. Radio Button or Ring ?)

(

Other test info (string control)

This test info will be written to the text fie.

When this info is entered then the program should proceed to the selected test mode.

If Constant Flow mode, then the set flow rate (ml/min) needs to be included in the

[mross]

I need to write a LabView program for somewhat of a basic test stand, but what like to get some ideas on how to impliment it . Here is an description / outline of the program reqiurements.

ETC.

When this info is entered then the program should proceed to the selected test mode.

If Constant Flow mode, then the set flow rate (ml/min) needs to be included in the

That is a great start. You definitely need to be able to lay out your goals like that.

The next step is to start eating the elephant one bite at a time. Each task has some code that causes it. You can write subvis for these tasks and test them as you go . You also want to put together your front panel UI early - even if you don't actually have subvis to feed them.. This way you work through what your user inputs and program outputs will be.

To the extent that you can simulate the various worldly activities your code chuncks will be less trouble as you assemble it all into one functioning whole.

I see this is your first post. You can't really expect someone to lay a vi on you that does what you want. It is too much. It will be a fair amount of work and we all have to pay our own way wherever we are. I can't do that on your program, nor can many of us. You need to start working and come back with smaller questions as you go.

Also you should let us know what hardware you are using: OS, and DAQ equipment PNs at the least. It could be importatnt to know the transducers you will have.

You should become acquainted with the User Event Driven Producer/Consumer architechture. This has a loop that watches for user inputs and a loop that runs at machine speed, doing daq, analysis and other execturive operations. It is possible to have several machine speed loops. It uses the "queue" functionality to sequence the actions based on user input. I am partial to the architecture becasue it gives a nice organization to the code.

Good luck,

Mike